By age 5, more than 10% of US children are obese and children from ethnic minority groups and more disadvantaged circumstances are disproportionately affected. While evidence exists that risk factors during pregnancy and early life are associated with childhood obesity, potential confounding in observational studies and small, restricted samples, present challenges to infer causation. There is debate about the extent to which these relationships apply to all racial/ethnic groups. Policies enacted to support healthy behaviors may actually increase disparities in the risk factors for obesity if they are adopted only by mothers from certain racial/ethnic groups or more advantaged groups. Few studies have addressed this concern. This K99/R00 award will provide an opportunity for the PI to build on her background in epidemiology and acquire training in causal inference, policy evaluation, and translating research into policy through formal courses and mentorship by an interdisciplinary group of renowned scholars. The overarching goals of this K award are to clarify peri- and post-natal risk factors for disparities in childhood obesity and to examine the effects of policies on disparities in these risk factors. This program of research will move forward the field of obesity prevention by maximizing the utility of public data through data linkage, integrating analytic techniques from economics and epidemiology to infer causality, understanding influences on racial/ethnic and socioeconomic disparities, and identifying policy drivers for behavior change. The PI will create a dataset of 215,000 children by linking Massachusetts birth certificate data to an electronic database of well-child visits. During the mentored phase of the award (K99), the PI will examine disparities in maternal smoking during pregnancy, excessive gestational weight gain, and breastfeeding as well as examine the associations between these risk factors and adiposity-related outcomes at ages 2 and 5 years. During the independent phase of the award (R00), the PI will examine the influence of policies on the prevalence and racial/ethnic and socioeconomic disparities in these risk factors, focusing on recent changes in tobacco control policies and gestational weight gain recommendations. Policies and programs for early childhood obesity prevention both in Massachusetts and nationally will be assessed to determine the extent to which factors during pregnancy and early life are included. The PI will present the findings from this program of research to policy makers in state government and help identify areas for future obesity prevention strategies. The PI will submit an R01 application during the fourth year of the award to continue to pursue these methods and interdisciplinary collaborations with the aim of pushing forward the research agenda on disparities in maternal and child health. PUBLIC HEALTH RELEVANCE: The aims of the program of research in this K99/R00 award are to address racial/ethnic and socioeconomic differences in perinatal and postnatal risk factors for childhood obesity and identify policy drivers for behavior change. The results will be presented to policy makers in state government to help identify areas for future obesity prevention strategies.